/*
 * Copyright (C) 2015 Drakeet <drakeet.me@gmail.com>
 *
 * This file is part of Meizhi
 *
 * Meizhi is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Meizhi is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Meizhi.  If not, see <http://www.gnu.org/licenses/>.
 */

package com.dementors.widget;

import android.content.Context;
import android.os.Build;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.FloatingActionButton;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewPropertyAnimatorListener;
import android.support.v4.view.animation.FastOutSlowInInterpolator;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;

public class ScrollAwareFABBehavior extends FloatingActionButton.Behavior {
  private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator();
  private boolean mIsAnimatingOut = false;

  public ScrollAwareFABBehavior(Context context, AttributeSet attrs) {
    super();
  }

  @Override public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout,
      final FloatingActionButton child, final View directTargetChild, final View target,
      final int nestedScrollAxes) {
    // Ensure we react to vertical scrolling
    return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL
        || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target,
        nestedScrollAxes);
  }

  @Override public void onNestedScroll(final CoordinatorLayout coordinatorLayout,
      final FloatingActionButton child, final View target, final int dxConsumed,
      final int dyConsumed, final int dxUnconsumed, final int dyUnconsumed) {
    super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed,
        dxUnconsumed, dyUnconsumed);
    if (dyConsumed > 0 && !this.mIsAnimatingOut &&
        child.getVisibility() == View.VISIBLE) {
      // User scrolled down and the FAB is currently visible -> hide the FAB
      animateOut(child);
    } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) {
      // User scrolled up and the FAB is currently not visible -> show the FAB
      animateIn(child);
    }
  }

  // Same animation that FloatingActionButton.Behavior uses to hide the FAB when the AppBarLayout exits
  private void animateOut(final FloatingActionButton button) {
    if (Build.VERSION.SDK_INT >= 14) {
      ViewCompat.animate(button)
          .scaleX(0.0F)
          .scaleY(0.0F)
          .alpha(0.0F)
          .setInterpolator(INTERPOLATOR)
          .withLayer()
          .setListener(new ViewPropertyAnimatorListener() {
            public void onAnimationStart(View view) {
              ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
            }

            public void onAnimationCancel(View view) {
              ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
            }

            public void onAnimationEnd(View view) {
              ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
              view.setVisibility(View.GONE);
            }
          })
          .start();
    } else {
      Animation anim = AnimationUtils.loadAnimation(button.getContext(),
          android.support.design.R.anim.design_fab_out);
      anim.setInterpolator(INTERPOLATOR);
      anim.setDuration(200L);
      anim.setAnimationListener(new Animation.AnimationListener() {
        public void onAnimationStart(Animation animation) {
          ScrollAwareFABBehavior.this.mIsAnimatingOut = true;
        }

        public void onAnimationEnd(Animation animation) {
          ScrollAwareFABBehavior.this.mIsAnimatingOut = false;
          button.setVisibility(View.GONE);
        }

        @Override public void onAnimationRepeat(final Animation animation) {
        }
      });
      button.startAnimation(anim);
    }
  }

  // Same animation that FloatingActionButton.Behavior uses to show the FAB when the AppBarLayout enters
  private void animateIn(FloatingActionButton button) {
    button.setVisibility(View.VISIBLE);
    if (Build.VERSION.SDK_INT >= 14) {
      ViewCompat.animate(button)
          .scaleX(1.0F)
          .scaleY(1.0F)
          .alpha(1.0F)
          .setInterpolator(INTERPOLATOR)
          .withLayer()
          .setListener(null)
          .start();
    } else {
      Animation anim = AnimationUtils.loadAnimation(button.getContext(),
          android.support.design.R.anim.design_fab_in);
      anim.setDuration(200L);
      anim.setInterpolator(INTERPOLATOR);
      button.startAnimation(anim);
    }
  }
}